m = int(input('m = '))
n = int(input('n = '))
fm = 1
for num in range(1, m + 1):
    fm *=  num
fn = 1
for num in range(1, n + 1):
    fn *= num
fm_n = 1
for num in range(1, m - n + 1):
    fm_n *= num
print(fm // fn //fm_n)